CROSS Safety Report
Parapet wall collapse
This report is over 2 years old
The sudden failure of parapet coping stones on an old two storey industrial building caused the stones to fall onto a road and pavement below.
Key Learning Outcomes
For building owners and managers:
Regular inspections and maintenance can help keep a structure safe and identify any obvious safety issues that need to be addressed
For civil and structural design engineers:
Be aware of the possibility of this type of failure (described in the report) on steep parapet slopes if you are carrying out inspections on similar structures
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The sudden failure of parapet coping stones on an old two storey industrial building caused the stones to fall onto a road and pavement below. A parked car was crushed but fortunately no one was injured. The 6m long parapet from ridge to eaves was at the top of a brick gable wall on the line of an approximately 45-degree roof slope (Figure 1 & 2). It was understood that the building had been recently inspected as part of a sale process, but no adverse comments had been made.
From a close examination of the parapet from a mobile platform, the collapse had been caused by failure of the eave’s parapet stone, according to the reporter. This stone was embedded horizontally into the wall and the parapet stones then prevented from sliding by an indent bearing into this stone with a vertical failure at the root of this indent. The reporter stated that the situation had been aggravated as the brickwork below the eaves stone appeared to have been heavily eroded (although this had been partly destroyed in the collapse) thus almost certainly also placing this stone into bending and shear in addition to the direct tension.
The opposing parapet was found to be in a similar condition from a close examination, while the parapet at the opposite gable end was found to be in reasonable condition. After the examination, it was decided to immediately remove all the remaining parapet stones and temporarily replace them with plastisol coated steel sheeting securely fixed to the brickwork. The reporter recommends that all structural engineers are aware of the possibility of this type of failure on steep parapet slopes and, if necessary, either replace or securely fix the coping stones.
After the examination, it was decided to immediately remove all the remaining parapet stones and temporarily replace them with plastisol coated steel sheeting securely fixed to the brickwork
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